The United Stated Environmental Protection agency and United States Army Corps of Engineers have been seeking a method for determining the chronic toxicity of fresh water and marine bottom sediment and pore water extracted therefrom. Although certain methods have been available for using invertebrate species for evaluating the toxicity of sediment and pore water by introducing active or developing animals to the sediment and/or pore water, these tests are limited in duration due to the physiological needs of the active invertebrates used. Moreover, there appears to be no known method that would provide for determining the toxicity of such sediment and/or pore water to dormant invertebrates over an extended period of time.